10.14.3.4 New Debugger Commands

The Prolog debugger is extended by FDBG.
The & debugger is modified, and two new commands are added:

&

& N

This debugger command is extended so that the annotated form of domain
variables is also printed when listing the variables with
blocked goals.

A

A Selector

Annotates and prints the current goal and a legend of the
variables appearing in it. If a selector is specified, the
subterm specified by it is assumed to be an action list, and
is taken into account when displaying the legend. For example: